1. Field
Embodiments of the present invention relate to wireless radio frequency systems and, in particular, to baluns in wireless radio frequency systems.
2. Discussion of Related Art
Many wireless radio frequency (RF) applications, such as televisions, wireless telephones, and personal digital assistants (PDAs), receive unbalanced, single-ended signals and convert them to balanced, differential signals for downstream processing. A line is unbalanced when the signal being transmitted over the line has ground as its reference potential. A line is balanced when the signal being transmitted over the line does not have ground as its reference potential.
Baluns are commonly used to convert unbalanced, single-ended signals to balanced, differential signals with each signal having substantially the same magnitude but being one hundred eighty degrees out of phase with each other. For example, it is typical to fine a balun is placed between a twisted pair of wires on a television antenna (balanced line) and the coaxial cable going to the television (unbalanced line). The term balun comes from combining the word “balanced” with the word “unbalanced.”
Baluns used in many present-day applications such as small, hand-held RF wireless devices have limitations, however. For example, they tend to be “expensive” components in that they are located on the dies of other components (e.g., on-die or on-silicon), and die space is very limited. Because they take up die space there is less space available for other on-die components.
This also means that on-die baluns also are limited in size in an effort to accommodate other on-die components. Size limitations limit the signal-to-noise ratio (SNR), signal sensitivity, and the quality (Q) factor of baluns.
Baluns used in many present-day applications such as small, hand-held RF wireless devices also tend to be low performance components. This is because as current flows through the small traces of the baluns some of the signal magnitude is lost due to heat dissipation and lossiness. The balanced, differential signal is thus degraded.